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(spot samples) during one to all three trimesters of pregnancy and the primary outcomes were the <br /> results of intelligence testing in their children at ages 4 (General Cognitive Index, GCI, of the McCarthy <br /> Scales of Children's Abilities, in Spanish) and at age 6-12 (Wechsler Abbreviated Scale of Intelligence, <br /> Full-Scale IQ (WASI-FSIQ)). In the discussion, the authors state that, "The associations with GCI <br /> appeared to be linear across the range of prenatal exposures, but there was some evidence that <br /> associations with IQ may have been limited to exposures above 0.8 mg/L." It is unclear to me whether <br /> their statistical analysis adequately controlled for the differences in maternal lead levels among the <br /> cohorts. The authors acknowledge that they did not have information about iodine sufficiency. <br /> While multiple studies have concluded that decrements in IQ are associated with exposure to <br /> high levels of fluoride in drinking water, there are far fewer studies that assess cognition and pre- or <br /> post-natal exposure to fluoride at low levels of exposure. The studies that show an adverse effect at <br /> high levels of exposure raise the question of adverse effects of low levels of exposure and concern for <br /> excessive exposure due to sources of ingested fluoride other than appropriately fluoridated drinking <br /> water. The study by Green et a15 found an association with IQ in boys, but not girls; they do not provide <br /> a biological explanation for this finding. While some of the studies include maternal lead exposure as a <br /> source of prenatal exposure for children, none of the studies reviewed address post-natal exposure of <br /> the child to lead, a known neurotoxin. One study by Malin and Till? looked at the percentage of <br /> fluoridation in different parts of the U.S. and parent-reported diagnoses of Attention Deficit <br /> Hyperactivity Disorder (ADHD) in their children. An association between having more areas with <br /> fluoridated drinking water (particularly added, rather than naturally-occurring fluoride in water) and a <br /> higher prevalence of children with a diagnosis of ADHD was found. The authors note the study limitation <br /> of lack of individual exposure data or information about whether the child lived in the same area at the <br /> 27 <br />